Boston Rainfall: 44 Inches Yearly, Evenly Distributed
Boston receives an average of 43.8 inches (1,112 mm) of precipitation annually, spread fairly evenly across seasons—unlike West Coast mediterranean or Southern monsoon patterns.
Monthly Distribution (1991–2020 Normals)
| Month | Avg Precip (in) | Character |
|---|
| Jan | 3.39 | Snow/rain mix |
| Feb | 3.21 | Snow/rain |
| Mar | 4.17 | Rain increasing |
| Apr | 3.63 | Rain |
| May | 3.25 | Rain |
| Jun | 3.22 | Rain, thunderstorms |
| Jul | 3.43 | Thunderstorms |
| Aug | 3.33 | Thunderstorms |
| Sep | 3.56 | Rain, tropical remnants |
| Oct | 3.94 | Rain, nor'easters begin |
| Nov | 4.03 | Rain, early snow |
| Dec | 4.63 | Snow/rain |
Key Points
- Wettest months: November–December, March–April (nor'easters, coastal storms).
- Driest months: July–August (but still 3.3+ in — convective storms).
- Snow: Avg 49 in/yr; highly variable (2015: 110 in; 2012: 9 in).
- Year-to-year swing: 2020: 60.7 in; 2016: 28.1 in.
Climate Change Signal
- Total precipitation ↑ ~10% since 1900.
- Heavy downpours (>2 in/day) ↑ 50% — infrastructure stress.
- More rain, less snow — earlier peak flows, winter flooding.
Boston doesn't have a "rainy season"—it has rain all year, with winter nor'easters and summer thunderstorms as the main drivers.
Wanderlust World